Rocker Motion-Powered Generators For Rocker-Mounted Electronic Devices

ABSTRACT

An internal combustion engine has a valvetrain that includes a rocker arm assembly on which is mounted an electronic device and at least a part of a generator. The generator converts some of the mechanical energy that is transmitted through the rocker arm assemblies into electricity. That electricity may be used to power an electric latch, a transmitter, or another type of rocker arm assembly-mounted electrical device. Various generator configurations are described. In some configurations, the generator is piezoelectric. In other configurations, the generator is electromagnetic. In some configurations, the generator is driven by force transmitted by the rocker arm assembly from a cam. In some configurations, the generator is driven by vibrations.

FIELD

The present teachings relate to valvetrains, particularly valvetrains providing variable valve lift (VVL) or cylinder deactivation (CDA).

BACKGROUND

Hydraulically actuated latches are used on some rocker arm assemblies to implement variable valve lift (WL) or cylinder deactivation (CDA). For example, some switching roller finger followers (SRFF) use hydraulically actuated latches. In these systems, pressurized oil from an oil pump may be used for latch actuation. The flow of pressurized oil may be regulated by an oil control valve (OCV) under the supervision of an Engine Control Unit (ECU). A separate feed from the same source provides oil for hydraulic lash adjustment. This means that each rocker arm has two hydraulic feeds, which entails a degree of complexity and equipment cost. The oil demands of these hydraulic feeds may approach the limits of existing supply systems.

SUMMARY

The complexity and demands for oil in some valvetrain systems can be reduced by replacing hydraulic latches with electric latches. But conventionally powering rocker arm assembly-mounted electric latches may involve attaching wire pairs to each of the rocker arm assemblies. Since the rocker arm assemblies are constantly reciprocating in proximity to other moving parts, wires may be caught, clipped, or fatigued and consequently short out.

The present teachings provide a valvetrain that includes a rocker arm assembly-mounted generator. The generator may convert some of the mechanical energy that is transmitted through the rocker arm assemblies into electricity. That electricity may be used to power electric latches or other rocker arm assembly-mounted electrical devices. Some of these teachings relate to specific generator configurations. Some of these teachings relate to having an electronic device that is powered by the generator and is also mounted to the rocker arm assembly. The electronic device may be considered in relation to any one of the specific generator configurations.

In some of these teachings, the electric power produced by the generator is stored prior to use. Power may be stored, for example, in a battery or capacitor. Storing power may allow a smaller generator to be used. A smaller generator may have a lower power rating than the peak power requirement of a device the generator powers. A storage device may have sufficient capacity to store at least the generator's maximum output over two cam rotations.

In some of these teachings, the rocker arm assembly has two states. For example, one state may be a latched state and another may be an unlatched state. A generator may produce power only when the rocker arm assembly is in one of the two states. The generator may charge a power storage device while the one state prevails and the power storage device may power an electrical device while the second state prevails.

According to some aspects of the present teachings, the generator is driven by a cam. In some of these teachings, the generator is a piezoelectric generator. The piezoelectric generator may be positioned in a pathway through which the rocker arm assembly transmits forces from the cam. The transmitted force may be comparatively large. Positioning the piezoelectric generator to transmit these forces may allow the generator to experience a large force variation as frequently as once each cam cycle. The generator may then provide sufficient power to support a wide range of applications.

In some of these teachings, the piezoelectric generator is configured to undergo compression in response to the cam rising off base circle and expansion in response to the cam descending toward base circle. In some of these teachings, the piezoelectric generator is configured to undergo a shear deformation in response to the cam rising off base circle and relief from that shear deformation in response to the cam descending toward base circle.

In some of these teachings, a piezoelectric generator is placed in a force transmission pathway between a cam shaft and a valve spring. In some of these teachings, a piezoelectric generator is placed in a force transmission pathway between a cam shaft and a spring stop for a lost motion spring on a rocker arm assembly. In some of these teachings, a piezoelectric generator is placed in a force transmission pathway between a cam shaft and a fulcrum on which a rocker arm of the rocker arm assembly pivots. In some of these teachings, a piezoelectric generator is placed in a force transmission pathway between a cam shaft and a rocker shaft on which a rocker arm of the rocker arm assembly pivots.

In some of these teachings, a piezoelectric generator is placed in an elephant's foot. In some of these teachings, a piezoelectric generator is placed in a hydraulic chamber, such as the hydraulic chamber of a hydraulic lash adjuster. In some of these teachings, a piezoelectric generator is placed between a spring and a spring stop. In some of these teachings, the rocker arm assembly comprises a first part mounted on a second part that is an axle, trunnion, or rocker shaft. In some of these teachings, the piezoelectric generator is positioned to transmit force between the first part and the second part. The mounting of the first part on the second part may permit relative rotation of the first part and the second part.

In some of these teachings, the piezoelectric generator is of the cantilever beam-type and is configured to undergo bending in a first direction in response to a cam rising off base circle and bending in a reverse direction in response to the cam descending back toward base circle. In some of these teachings, an end of the generator is coupled to a rocker arm. In some of these teachings, an end of the generator is coupled to a torsion spring.

According to some aspects of the present teachings, a piezoelectric generator is mounted on a rocker arm assembly and structured to produce electricity from vibration of the rocker arm assembly. In some of these teachings, the vibration-driven piezoelectric generator is of the cantilever beam type. In some other of these teachings, the vibration-driven piezoelectric generator is of the spring and proof mass type. A vibration-driven piezoelectric generator may cycle much more rapidly that the rotation of a cam shaft allowing power pulses to be produced at much greater frequency than that of the cam shaft's rotation.

According to some aspects of the present teachings, a first component of an electromagnetic generator, including a coil and a pole, is mounted on a first part of a rocker arm assembly. A second component of the electromagnetic generator may be mounted on another part of the rocker arm assembly or on another part separate from the rocker arm assembly. The electromagnetic generator may include a coil and a magnet. The coil and magnet may be configured to move relative to one another in a first direction as a cam is rising off base circle and in the opposite direction as the cam is descending toward base circle. A cam may do a comparatively large amount of work on a rocker arm assembly. A fraction of that work converted into electricity by a generator may be sufficient to power a wide range of electrical devices.

In some of these teachings, a first component of the electromagnetic generator is mounted to a reciprocating part. The reciprocating part may be a lifter. In some of these teachings, a first component and a second component of the electromagnetic generator are structured to pivot relative to one another. One of the components may be fixed to a first part such as a rocker arm, elephant's foot, or scaffold. The other of the components may be fixed to a second part on which the first part pivots. The second part may be a trunnion, an axle, or a rocker shaft.

In some of these teachings, an electromagnetic generator includes a first component and a second component structured to rotate relative to one another. The rocker arm assembly may include a cam roller. One of the components may be fixed to rotate with the cam roller while the other component is fixed to a non-rotating part of the rocker arm assembly.

In some of these teachings, the electromagnetic generator includes a spring and proof mass with the proof mass providing a magnetic component of the generator. In comparison to a piezoelectric generator of the spring and proof mass type, the electromagnetic generator may have a greater power-producing capacity due to the larger range of motion of the proof mass in comparison to the length over which a piezoelectric generator may deform. In some of these teachings, the generator is tuned for the proof mass to oscillate at approximately a cycling rate for the rocker arm assembly.

According to some aspects of the present teachings, a generator a part of which is mounted to a rocker arm assembly is configured to power an electrical device that is also mounted to the rocker arm assembly. The electrical device is a distinct device from the generator. In some of these teachings, the electrical device includes a transmitter. In some of these teachings, the electrical device includes an amplifier. In some of these teachings, the electrical devices provides diagnostic information based on the timing with which the generator produces power. In some of these teachings, the electrical device is a sensor. In some of these teachings, the electrical device includes a solenoid. In some of these teachings, the electrical device is an electromagnetic latch.

In some of these teachings, the electrical device is mounted so that there is little or no movement between the electrical device and a pole of the generator. In some of these aspects, the electrical device and the pole of the generator are held in rigid relationship. These arrangements may facilitate keeping wires connecting between the generator and the electrical device from being caught, clipped, or fatigued.

According to some aspects of the present teachings, a rocker arm assembly may be adapted to receive a generator without modification to any casting or stamping equipment. Rocker arms of the assembly may be made using casting or stamping equipment that has been designed to build parts for a rocker arm assembly that does not include a generator. The components produced by the casting and stamping equipment may be cast and stamped without any adaptations to receive generator components. The same casting and stamping equipment that has been used to manufacture components of a rocker arm assembly without a generator may then be reused to manufacture components of a rocker arm assembly with a generator as provided by the present teachings.

The primary purpose of this summary has been to present broad aspects of the present teaching in a simplified form to facilitate understanding of the present disclosure. This summary is not a comprehensive description of every aspect of the present teachings. Other aspects of the present teaching will be conveyed to one of ordinary skill in the art by the following detailed description together with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates a valvetrain according to some aspects of the present teachings.

FIG. 1B illustrates the valvetrain of FIG. 1A with the cam off base circle.

FIG. 2A illustrates an OHV valvetrain to which the present teaching may be applicable.

FIG. 2B illustrates the OHV valvetrain of FIG. 2A with the cam off base circle.

FIG. 3A illustrates an end pivot OHC valvetrain to which the present teaching may be applicable.

FIG. 3B illustrates the end pivot OHC valvetrain of FIG. 3A with the cam off base circle.

FIG. 4A illustrates a direct acting OHC valvetrain to which the present teaching may be applicable.

FIG. 4B illustrates the direct acting OHC valvetrain of FIG. 4A with the cam off base circle.

FIG. 5A illustrates a DHLA according to some aspects of the present teachings.

FIG. 5B illustrates the DHLA of FIG. 5A in an unlatched and compressed state.

FIG. 6A illustrates with a top view a switching rocker arm to which the present teaching may be applicable.

FIG. 6B illustrates with a side view the switching rocker arm of FIG. 6A while a cam is on base circle.

FIG. 6C illustrates with a side view the switching rocker arm of FIG. 6A in an unlatched state while the cam is off base circle.

FIG. 6D illustrates with a side view the switching rocker arm of FIG. 6A in a latched state while the cam is off base circle.

FIG. 7 illustrates another switching rocker arm to which the present teachings may be applicable.

FIG. 8 illustrates an HLA according to some aspects of the present teachings.

FIG. 9 illustrates another HLA according to some aspects of the present teachings.

FIG. 10 illustrates a piezoelectric generator mounted to an elephant's foot according to some aspects of the present teachings.

FIG. 11 illustrates a piezoelectric generator mounted between a trunnion and a rocker arm according to some aspects of the present teachings.

FIG. 12 illustrates a piezoelectric generator mounted between a torsion spring and a spring stop according to some aspects of the present teachings.

FIG. 13A illustrates with a top view a piezoelectric generator according to some aspects of the present teachings mounted to bend with a torsion spring.

FIG. 13B illustrates with a side view the piezoelectric generator of FIG. 13A with a cam on base circle.

FIG. 13C illustrates with a side view the piezoelectric generator of FIG. 13A with the cam off base circle.

FIG. 14 illustrates a piezoelectric generator configured to undergo shear deformation according to some aspects of the present teachings.

FIG. 15 illustrates a spring-mass piezoelectric generator according to some aspects of the present teachings.

FIG. 16A illustrates a cantilever beam piezoelectric generator according to some aspects of the present teachings.

FIG. 16B illustrates another cantilever beam piezoelectric generator according to some aspects of the present teachings.

FIG. 17 illustrates a rocker arm assembly with an electromagnetic generator according to some aspects of the present teachings.

FIG. 18 illustrates an electromagnetic generator mounted to a pair of rocker arm assembly parts that undergo relative pivoting or rotation according to some aspects of the present teachings.

FIG. 19 illustrates another electromagnetic generator mounted to a pair of rocker arm assembly parts that undergo relative pivoting or rotation according to some aspects of the present teachings.

FIG. 20 illustrates a spring-mass type electromagnetic generator according to some aspects of the present teachings.

FIG. 21 provides a flow chart of a rocker arm assembly manufacturing method according to some aspects of the present teachings.

DETAILED DESCRIPTION

FIGS. 1A and 1B schematically illustrate a valvetrain 101 including a rocker arm assembly 110 according to some aspects of the present teachings. A generator 137, or at least a portion thereof including pole 138, may be mounted on rocker arm assembly 110. In some aspects of the present teachings, generator 137 may be grounded to rocker arm assembly 110. But pole 138 is not so grounded.

An electrically powered device 151 and optionally an electrical energy storage device 127 may also mounted on rocker arm assembly 110. Generator 137 may be a device that produces electricity from mechanical energy. Examples for generator 137 include electromagnetic and piezoelectric generators. Examples for energy storage device 127 include batteries and capacitors. Examples for electrical device 151 include solenoids, receivers, and amplifiers. Pole 152 of electrical device 151 may be coupled to pole 138 of generator 137. Pole 152 and pole 138 may both be coupled to an energy storage device 127 that is charged by generator 137.

Valvetrain 101 may include a valve 103 and a cam shaft 125 on which is mounted an eccentrically shaped cam 123. Rocker arm assembly 110 may include a cam follower 121. Rocker arm assembly 110 may be structured and configured to actuate valve 103 in response to rotation of cam 123. As the term is used in the present disclosure a “rocker arm assembly” may be any assembly of components that is structured and positioned in that way. Accordingly, examples for rocker arm assembly 110 include examples without rocker arms.

Valve 103 may be a poppet valve having a valve spring 105 acting on valve 103 through valve stem-mounted spring stop 107. Valve spring 105 may bias valve 103 upwardly with respect to a surface 104 of an engine block (not shown). In FIG. 1A eccentrically shaped cam 123 is on base circle whereas in FIG. 1B eccentrically shaped cam 123 is at maximum lift. When cam 123 is on base circle, valve 103 may be on its seat 109 as shown in FIG. 1A. When cam 123 is at peak lift, valve spring 105 may be compressed between spring stop 107 and surface 104 and valve 103 may be lifted off its seat 109 as shown in FIG. 1B. Whether or not valve 103 lifts of its seat 109 (is actuated) in response to rotation of cam 123 in any particular cam cycle may depend on a state of rocker arm assembly 110, such as a state of being either latched or unlatched.

In some aspects of the present teachings, valvetrain 101 may be an overhead valve (OHV) valvetrain 101A, for which FIGS. 2A and 2B provide an example. OHV valvetrain 101A may include a rocker shaft 111 and a rocker arm assembly 110A. Rocker arm assembly 110A may include a lifter 115 and a rocker arm 113 that is mounted on rocker shaft 111. Lifter 115 may include a hydraulic lash adjuster 117 and a roller follower 121A. A roller follower 121A is an example for cam follower 121.

In OHV valvetrain 101A, cam shaft 125 may rotate to actuate valve 103 via eccentrically shaped cam 123. As cam 123 rises off base circle, it may transmit a force 124 from cam shaft 125 onto lifter 115. Lifter 115 may retransmit this force resulting in an approximately equal force 108B on second end 112B of rocker arm 113. Second end 112B may rise in response and, through leverage on rocker shaft 111, compress valve spring 105 and drive valve 103 off its seat 109. Valve spring 105 may produce a reactionary force 108A on first end 112A of rocker arm 113. Rocker shaft 111 may produce a reactionary force 108C, which acts downwardly on rocker arm 113 to balance out the upward forces 108A and 108B. These forces may increase as cam 123 rises off base circle and decrease as cam 123 descends back toward base circle. Generator 137 may be positioned to be acted upon and actuated by any one of these forces.

In some aspects of the present teachings, valvetrain 101 may be an end pivot overhead cam (OHC) valvetrain 101B, for which FIGS. 3A and 3B provide an example. End pivot OHC valvetrain 101B may include a rocker arm assembly 110B. Rocker arm assembly 110B may include a rocker arm 113, a roller follower 121A, and a hydraulic lash adjuster 117. Hydraulic lash adjuster 117 may provide a fulcrum on which rocker arm 113 pivots.

In end pivot OHC valvetrain 101B, cam shaft 125 may rotate to actuate valve 103 through eccentrically shaped cam 123. As cam 123 rises off base circle, it may transmit a force 124 from cam shaft 125 through cam follower 121A and trunnion 119B, on which cam follower 121A is mounted, to produce a downward force 108C on rocker arm 113. Rocker arm 113 may descend in response, pivoting on HLA 117, compressing spring 105, and driving valve 103 off its seat 109. Valve spring 105 may produce a reactionary upward force 108A on first end 112A of rocker arm 113. HLA 117 may produce a reactionary upward force 108B on second end 112B of rocker arm 113. Generator 137 may be positioned to be acted upon and actuated by any one of these forces.

While in most aspects of the present teaching rocker arm assembly 110 includes a rocker arm 113, some aspects of the present teachings may be applied to a direct acting overhead cam (OHC) valvetrain 101C, for which FIGS. 4A and 4B provide an example. Direct acting OHC valvetrain 101C may include a rocker arm assembly 110C. Rocker arm assembly 110C may include hydraulic lash adjuster 117 and a slider 121B. Slider 121B is another example for cam follower 121.

In direct acting OHC valvetrain 101C, cam shaft 125 may rotate to actuate valve 103 through eccentrically shaped cam 123. As cam 123 rises off base circle, it may transmit a force 124 from cam shaft 125 through slider 121B to produce a downward force 108C on HLA 117. HLA 117 may descend in response, which may drive valve 103 off its seat 109. Valve spring 105 may produce a reactionary upward force 108A on HLA 117 as valve spring 105 compresses. Generator 137 may be positioned to be acted upon and actuated by any one of these forces.

In some aspects of the present teachings, HLA 117 in direct acting OHC valvetrain 101C, or in one of the other examples for valvetrain 101, may be a deactivating hydraulic lash adjuster (DHLA) 117A, for which FIGS. 5A and 5B provide an example. DHLA 117A may include an outer sleeve 131, a middle sleeve 139, and an inner sleeve 141 in nested sliding relation. Relative movement of inner sleeve 141 and middle sleeve 139 may provide lash adjustment.

A latch 133 may have a first position in which middle sleeve 139 and outer sleeve 131 are latched together and a second position in which middle sleeve 139 and outer sleeve 131 can slide relative to one another. A latch actuator 151A, which is an example for electrical device 151, may be used to actuate latch 133 for selective cylinder activation or deactivation. In the latched state, which is shown in FIG. 5A, DHLA 117A may be substantially rigid and functional to transmit or redirect force from cam 123 in such a way that valve 103 may be actuated. In the unlatched state, DHLA 117A may prevent valve 103 from being actuated by yielding in response to longitudinal force as shown in FIG. 5B. Yielding of DHLA 117A as cam 123 rises off base circle may be resisted by a lost motion spring 153, which takes up energy. Lost motion spring 153 may re-extend DHLA 117A and return energy to cam shaft 125 as cam 123 descends back toward base circle. The spring constant of lost motion spring 153 may be selected so that it yields before valve spring 105.

Hydraulic lash adjustment may be implemented using a hydraulic chamber 148 that is configured to vary in volume as DHLA 117A extends or contracts through relative motion of inner sleeve 141 and middle sleeve 139. A supply chamber 144 may be filled with hydraulic fluid from supply port 146. The hydraulic fluid may be engine oil, which may be supplied at a pressure of about 2 atm. When cam 123 is on base circle, check valve 147 may admit oil into hydraulic chamber 148. The oil may fill hydraulic chamber 148, extending DHLA 117A until there is no lash between cam 123 and cam follower 121. As cam 123 rises off base circle, DHLA 117A may be compressed. The pressure in hydraulic chamber 148 may rise and result in check valve 147 closing. DHLA 117A may then become relatively stiff, with inner sleeve 141 and middle sleeve 139 held in a substantially rigid relationship by substantially incompressible hydraulic fluid in hydraulic chamber 148. The pressure in hydraulic chamber 148 may become high as force is transmitted through DHLA 117A hydraulically.

In some aspects of the present teachings, electrical device 151 includes a solenoid. DHLA 117A includes an electric latch actuator 151A, which is an example of an electrical device 151 that includes a solenoid. An electrically controlled hydraulic valve may provide another example of an electrical device 151 that includes a solenoid. An electrically controlled hydraulic valve may be configured to actuate a hydraulic latch, which may provide a lower power alternative to electric latch actuator 151A and allow the use of a smaller generator 137. A hydraulic latch switched by an electrically controlled valve may use the same hydraulic feed as the one used for hydraulic lash adjustment.

In some aspects of the present teachings, electrical device 151 includes a transmitter. A transmitter may be used to communicate diagnostic information. In some of these teachings, these teachings, the transmitter includes and antenna. In some of these teachings, the transmitter includes an electronic oscillator. In some of these teachings, the electronic oscillator includes an LC oscillator circuit. In some of these teachings, the diagnostic information relates to the state of a switching or cylinder deactivating rocker arm. The state may relate to whether a pair of rocker arms are latched or unlatched. In some of these teachings, the diagnostic information relates to valve timing. In some of these teachings, the information may be determined from the output of generator 137 itself. In some of these teachings, electrical device 151 includes a sensor that provides diagnostic information. In some of these teachings, electrical device 151 includes an amplifier. An amplifier may be used to amplify a sensor signal.

In some aspects of the present teachings, rocker arm assembly 110 may include a switching rocker arm 113A. A switching rocker arm 113A may provide another example in which electrical device 151 may be an electric latch actuator 151A. FIGS. 6A-6D provide an example of a switching rocker arm 113A that may be suitable for an OHC valvetrain 101B.

In some aspects of the present teachings, a switching rocker arm 113A may include an inner rocker arm 113B and an outer rocker arm 113C. Inner arm 113B and outer arm 113C may be pivotally coupled through a trunnion 119B. Trunnion 119B may be an axle mounted on bearings or may be rigidly coupled to inner arm 113B or outer arm 113C. In the example of FIGS. 6A-6D, an elephant's foot 155 may also be mounted on trunnion 119B. Elephant's foot 155 contacts the stem of valve 103 and pivots with or on trunnion 119B to maintain a fixed orientation relative to valve stem 103.

In some aspects of the present teachings, a switching rocker arm 113A includes a torsion spring 157. A torsion spring 157 may be mounted on a trunnion 119C. Torsion spring 157, or a pair thereof, may be configured to bias inner arm 113B to pivot relative to outer arm 113C about trunnion 119B. In the example of FIGS. 6A-6D, a first end 159 of torsion spring 157 may abut a spring stop 161 formed into outer arm 113C. A second end 163 of torsion spring 157 may abut a trunnion 119A coupled to inner arm 113B. Trunnion 119A may be fixed to inner arm 113B, or inner arm 113A may be rotatably mounted on trunnion 119A. A rotatable mounting may include a bearing. Cam roller follower 121A may also be mounted on trunnion 119A. Trunnion 119A may be an axle.

A latch 133 and latch actuator 151A may be mounted on one of inner arm 113B and outer arm 113C. Latch 133 may be configured to selectively engage the other of inner arm 113B and outer arm 113C. It should be appreciated that the present teaching are applicable to many switching rocker arms designs, including ones in which the roles of inner arm 113B and outer arm 113C are reversed.

FIG. 6B illustrates switching rocker arm 113A when cam 123 is on base circle. In this position, latch 133 may be actuated between a retracted position and an extended position. If cam 123 rises off base circle while latch 133 is retracted, inner arm 113B may pivot relative to outer arm 113C as shown in FIG. 6C. Work done by cam 123 on rocker arm assembly 110 may cause torsion spring 157 to wind without compressing valve spring 105. In some aspects of the present teachings, valve 103 may remain seated and cylinder deactivation thereby implemented. In some other aspects of the present teachings, one or more other cams (not shown) may act on outer arm 113B to provide a shortened valve opening period, whereby a valve timing may be changed by retracting latch 133.

If cam 123 rises off base circle while latch 133 is extended, inner arm 113B may engage with latch 133, whereby relative motion of inner arm 113B and outer arm 113C may become restricted. A scaffold or an elephant's foot may support outer arm 113C on HLA 117A. A scaffold (not shown) may be integral with outer arm 113C or may be a separate part positioned between outer arm 113C and HLA 117. With latch 133 extended and arms 113B and 113C engaged, arms 113B and 113C may pivot as a unit on HLA 117, which provides a fulcrum supported at its base by a cylinder block (not shown). The rising of cam 123 may then result in arms 113B and 113C levering down on elephant's foot 155, compressing valve spring 105, and lifting valve 103 off its seat 109 as shown in FIG. 6D.

FIG. 7 illustrates switching rocker arm 113D, which is another example for rocker arm 113. Switching rocker arm 113D includes an inner rocker arm 113B and an outer rocker arm 113C. An electric latch actuator 151A may be mounted on inner arm 113B. A cam 123 (not shown) may be position to act on roller follower 121A. Other cams (not shown) may be position to act on slides 121B. When latch 133 is extended to engaged outer arm 113C, valve 103 may be opened by lifting either inner arm 113B or outer arm 113C. When latch 133 is retracted, it may be that only lifting of inner arm 113B will open valve 103.

In valvetrain 101, cam shaft 125 may do work on rocker arm assembly 110 as cam 123 rises off base circle. Most of that energy may be stored in one or more springs such as valve spring 105, lost motion spring 153, and torsion spring 157. Some of that stored energy may be returned to cam shaft 125 as cam 123 descends back toward base circle. But in some aspects of the present teachings, generator 137 may be driven by cam 123. In some aspects of the present teachings, a portion of the work done by cam shaft 125 on rocker arm assembly 110 may be work done on generator 137. The proportion may be less than 5% so as to have negligible effect on the operation of valvetrain 101. The proportion may be 0.1% or greater so as to provide an amount of energy sufficient to power many types of devices that may be the electrical device 151.

The lifting force 124 applied by cam shaft 125 on rocker arm assembly 110 through cam 123 may be 1 kN or more. The displacement provided by cam 123 may be on 1 cm or more. The number of displacements per second may be 10 or more. Accordingly, cam shaft 125 may do work on rocker arm assembly 110 at a rate of 100 J/s (Watts) or more. In some aspects of the present teachings generator 137 may have a capacity to produce from 10-500 mJ per rotation of cam shaft 125. Generator 137 may produce electrical power at a rate in the range from 100 mW to 5 W. Power production at a lower rate may be insufficient to support some of the applications contemplated by the present teachings. Power production at a greater rate may be redundant.

In some aspects of the present teachings, generator 137 may be a piezoelectric generator 137A positioned within rocker arm assembly 110 at a location where piezoelectric generator 137A may be subjected to a compressive force. In some of these aspects, the position is such that the force varies in approximate proportion to a force exerted by cam shaft 125 on rocker arm assembly 110. That approximate proportionality may be maintained at all times or just when rocker arm assembly 110 is in a certain state, such as a latched state or an unlatched state.

A position in which a piezoelectric generator 137A undergoes a force that varies in approximate proportion to a force exerted by cam shaft 125 on rocker arm assembly 110 may be a pathway along which rocker arm assembly 110 transmits force. In some aspects of these teachings, the force transmission may be between cam 123 and a spring. The spring may be valve spring 105, lost motion springs 153, or torsion spring 157. In some aspects of these teachings, the force transmission pathway is between cam 123 and a rocker shaft 111. In some aspects of these teachings, the force transmission pathway is between cam 123 and a base of a fulcrum on which a rocker arm 113 pivots.

In some aspects of these teachings, a piezoelectric generator 137A may be placed within a hydraulic chamber 148. In some of these aspects, the hydraulic chamber 148 is within an HLA 117, which may be DHLA 117A for which FIGS. 5A and 5B provide an example. DHLA 117A may transmit a force of 1 kN or greater. Hydraulic chamber 148 may have a cross-sectional area in the range from 1 to 10 cm². The pressure in hydraulic chamber 148 may rise into the range from 0.2 MPA to 40 MPa (400 atm). In some examples, the pressure in hydraulic chamber 148 may rise into the range from 1 MPA to 10 MPa (100 atm).

A piezoelectric generator 137A may have many possible configurations within a hydraulic chamber 148. The pressure in hydraulic chamber 148 may be substantially isotropic, which may allow piezoelectric generator 137A to have any orientation. Check valve 147 may be supported on a platform 149 abutting generator 137A. Alternatively, platform 149 may be fixed to the sides of hydraulic chamber 148. An advantage of placing piezoelectric generator 137A in hydraulic chamber 148 is that piezoelectric generator 137A may be strained in a highly uniform manner.

In some aspects of the present teachings, a non-grounded pole 138 of generator 137 and a non-grounded pole 152 of electrical device 151 are held in rigid relationship to each other through the rocker arm assembly 110. In some of these aspects, the poles 138 and 152 are attached to an integral part of rocker arm assembly 110. FIGS. 5A and 5B provide an example. Generator 137A, including its pole 138, and electric latch actuator 151A, including its pole 152, may both be attached to middle sleeve 139. The two poles 138 and 152 may be connected through energy storage device 127. The rigid relationship may minimize or eliminate movement of wires 145 that connect these devices.

In some aspects of the present teachings, a pole 138 of generator 137 and a pole 152 of electrical device 151 may be on independently moving parts of rocker arm assembly 110, but are still arranged to provide little movement of any connecting wires 145. In some of these aspects, pole 138 and pole 152 do not vary substantially in distance from one another as rocker arm assembly 110 cycles. FIG. 8 provides an example. In FIG. 8, an HLA 117B is shown having an annular-shaped piezoelectric generator 137A attached to inner sleeve 141 forming an upper part of hydraulic chamber 148. In this configuration, piezoelectric generator 137A may experience little movements relative to a rocker arm 113 positioned to pivot on HLA 117B.

In some aspects of the present teachings, a wire connecting a device on HLA 117 may pass through a joint at which a rocker arm 113 pivots on an HLA 117. FIG. 8 provides an example. Rocker arm 113 may include a scaffold 156 shaped to keep rocker arm 113 from slipping off HLA 117B while allowing rocker arm 113 to pivot on HLA 117B. A wire 145 may connect a generator 137A on HLA 117B to an electrical device 151 mounted on rocker arm 113. Wire 145 may pass out of HLA 117B through an opening 142 formed in the part of HLA 117 that abuts scaffold 156. In this example, the abutting part is an upper part of inner sleeve 141. Opening 142 mates with an opening 158 formed in scaffold 156. Opening 142 may be circular in cross-section. Opening 156 may be dish-shaped. This configuration protects wire 145 and allows wire 145 to experience little movement during operation of valvetrain 101.

In some aspects of these teachings, a piezoelectric generator 137A may be positioned within an HLA 117, a lifter 115, or another longitudinal force-transmitting member of a rocker arm assembly 110 in a configuration where the piezoelectric generator 137A transmits force longitudinally. FIG. 9 provides an example. In the example of FIG. 9, piezoelectric generator 137A may be positioned within an HLA 117C, but is not positioned within a hydraulic chamber 148. In this example, inner sleeve 141 may be provided as an upper portion 141B and a lower portion 141A with piezoelectric generator 137A sandwiched in between. All of the force transmitted upward by HLA 117B may pass through piezoelectric generator 137A.

In some aspects of the present teachings, a support structure 143 may be configured in parallel with piezoelectric generator 137A. In some of these aspects, support structure 143 may be configured whereby the sharing of a load between support structure 143 and piezoelectric generator 137A shifts in favor of support structure 143 if piezoelectric generator 137A is deformed beyond a certain point. For example, support structure 143 may be more rigid than piezoelectric generator 137A, but slightly shorter than piezoelectric generator 137A when neither is being compressed. Once piezoelectric generator 137A is compressed to a certain point, the heights may become equal and the load may shift to support structure 143.

In some aspects of these teachings, a piezoelectric generator 137A may be positioned between a rocker arm 113 and either a lifter 115, a valve 103, a rocker shaft 111, a cam follower 121, or an HLA 117 or like structure providing a fulcrum for the rocker arm 113. In some of these aspects, an elephant's foot 155 or a scaffold 156 may be positioned between the rocker arm 113 and the other part. In some of these aspects, piezoelectric generator 137A may abut an elephant's foot 155 or a scaffold 156.

In some aspects of the present teachings, piezoelectric generator 137A may be formed into an elephant's foot 155 or a scaffold 156. FIG. 10 provides an example. In FIG. 10, a piezoelectric generator 137A may be mounted in an elephant's foot 155. Elephant's foot 155 may be coupled to a rocker arm 113 through a trunnion 119A. Elephant's foot 155 may transmit force 108 from a rocker arm 113 to valve 103. Piezoelectric generator 137A may be positioned so that all or part of the force 108 is transmitted through it. As shown in FIG. 10, pole 138 of piezoelectric generator 137A may be connected by wire 145 to a pole 152 of an electrical device 151 that is also mounted on elephant's foot 155.

Electrical device 151 may be mounted on a rocker arm 113. Mounting electrical device 151 to a first component of a rocker arm assembly 110 and mounting generator 137 to a second component of rocker arm assembly 110 wherein the first and second components are joined through a trunnion 119 or other structure fixing both components to pivoting about a shared axis may enable a connection between electrical device 151 and generator 137 to be made with little movement of wire 145.

In some aspects of the present teachings, a piezoelectric generator 137A may be positioned between a trunnion 119 or a rocker shaft 111 and a part mounted on the trunnion 119 or rocker shaft 111. FIG. 11 provides an example in which the mounted part may be a rocker arm 113. Other examples of parts that may be mounted include a cam roller follower 121A and an elephant's foot 155. Several parts of a rocker arm assembly 110 may be mounted to a single trunnion 119. All of the mountings may include bearings and permit rotation. Some of the mountings may be fixed. The structure of FIG. 11 may be applied to either a mounting that is fixed or a mounting that permits rotation. In some aspects of the present teachings, a bearing 171 may be included in the mounting to permit relative rotation of the trunnion 119 or rocker shaft 111 and the mounted part.

As shown in FIG. 11, a mounting adapter 169 may fit a circular opening in rocker arm 113. Mounting adapter 169 may have an opening 170 with vertical sidewalls. A mounting adapter 175 may fit around rocker shaft 111 and optionally a bearing 171 adapting them to fit within opening 170 in a sliding relationship. Mounting adapter 175 may also serve to apply forces 108 from rocker shaft 111 evenly across piezoelectric generator 137A. Piezoelectric generator 137A may be positioned between mounting adapter 169 and mounting adapter 175. This arrangement may allow a small amount of relative movement in a vertical direction between mounting adapter 175 on rocker shaft 111 and mounting adapter 169 of rocker arm 113. This relative movement may allow for expansion and contraction of piezoelectric generator 137A. A spring clip 173 may facilitate maintaining the attachment between rocker shaft 111 and rocker arm 113 while allowing this relative movement to occur.

In some aspects of the present teachings, a piezoelectric generator 137A may be positioned to be acted upon by a torsion spring 157. FIG. 12 provides an example in which piezoelectric generator 137A may be positioned between first end 159 of torsion spring 157 and spring stop 161. As another example, piezoelectric generator 137A may be positioned adjacent second end 163 of torsion spring 157. The positioning may place piezoelectric generator 137A between end 163 and trunnion 119A. In some aspects of these teachings, piezoelectric generator 137A may be positioned to receive a force equal to a winding force on torsion spring 157. The forces on a torsion spring 157 may have a magnitude and cycling rate useful for driving piezoelectric generator 137A. Moreover, one or the other end of torsion spring 157 may provide a convenient location for mounting piezoelectric generator 137A.

In some aspects of the present teachings, a piezoelectric generator 137A is configured to be actuated by a bending force. In these aspects, piezoelectric generator 137A may be bent by the relative movement of two parts of a rocker arm assembly 110 or by the bending of a torsion spring 157. FIGS. 13A-13C provide an example. A first end 194 of generator 137 may be held in a fixed relationship with HLA 117 by bracket 195. A second end 192 of generator 137 may be held in a fixed relationship with end 163 of torsion spring 157 by bracket 193. As shown in FIG. 13C, as cam 123 rises off base circle, piezoelectric generator 137A may be bent over torsion spring 157. While many other configurations are possible, this configuration has the advantage that piezoelectric generator 137A will be bent and unbent with each rotation of cam 123 regardless of whether rocker arm 113A is in a latched or unlatched state.

Piezoelectric generator 137A may be made from any suitable piezoelectric material. Examples of materials that may be suitable include ceramics. In some aspects of the present teachings, the piezoelectric material is a form of lead zirconate titanate (PZT). The material may be selected to be effective at a maximum operating temperature for the valvetrain 101. That temperature may be at least 100° C. The material may be selected in view of its cost, its energy density, its effective coupling factor, and its depolarization stress.

A greater cross-sectional area of piezoelectric generator 137A allows a piezoelectric material having a lower depolarization stress to be used. In some aspects of the present teachings, piezoelectric generator 137A is provided with a greater cross-sectional area to reduce the peak stress on the piezoelectric material. In some aspects of these teachings, rocker arm assembly 110 widens at a location where piezoelectric generator 137A is interposed.

In some aspects of the present teachings, a piezoelectric generator 137A is configured to be actuated by shear stress. FIG. 14 provides an example. FIG. 14 shows an HLA 117C. Like HLA 117B of FIG. 9, HLA 117C has an inner sleeve 141 provided as two parts, a lower inner sleeve 141A and an upper inner sleeve 141B. In HLA 117C, inner sleeve 141A and upper inner sleeve 141B may be joined by piezoelectric generator 137A across a gap 140 that extends longitudinally. Longitudinal force transmission through HLA 117C may then result in shear stresses 114 on piezoelectric generator 137A. Configuring a piezoelectric generator 137A to be actuated by shear stresses may have the advantages of facilitating spreading of force transmission over a wide area of piezoelectric material.

A piezoelectric material may have a maximum amount of energy that it can produce per cycle per unit volume. Thus, given a target amount of energy production and a cycle rate, the volume of a given piezoelectric material required for piezoelectric generator 137A may be determined. Given a maximum cross-sectional area for piezoelectric generator 137A, a thickness may then be determined. In some aspects of the present teachings, the thickness of a piezoelectric material used in piezoelectric generator 137A is 0.5 cm or more.

Many piezoelectric materials are capable of sustaining a cycle rate one or more orders of magnitude higher than a maximum cycle rate of a rocker arm assembly 110. In some aspects of the present teachings, a generator 137 may be a piezoelectric generator configured to cycle at a much higher rate than rocker arm assembly 110. In some of these aspects, generator 137 is configured to be driven by vibration of rocker arm assembly 110. A generator 137 operating off vibrations may cycle much more quickly than one actuated by cam 123. Much less energy is available through vibration, which may limit the range of electrical devices 151 suitable for use with a piezoelectric generator 137 driven by vibration. But a piezoelectric generator 137 driven by vibration may achieve a given rate of power generation with less piezoelectric material than one that is driven by cam 123.

FIG. 15 provides an example of a vibration-driven piezoelectric generator 137C. A vibration-driven piezoelectric generator 137C may include a proof mass 177 and a spring 179 within a housing 183. Proof mass 177 may be configured to compress a piezoelectric material 181 as shown in FIG. 15. As shown in FIG. 15, vibration-driven piezoelectric generator 137C may be mounted on an elephant's foot 155, which may be positioned to act on a valve 103 (not shown in this figure). Other locations that may be suitable for vibration-driven piezoelectric generator 137C include on a rocker arm 113, on an HLA 117, and on a lifter 115.

A vibration-driven piezoelectric generator 137C may be a cantilever beam vibration-driven piezoelectric generator 137D, for which FIGS. 16A and 16B provide examples. For cantilever beam vibration-driven piezoelectric generator 137D, the beam 185 itself may operate as a proof mass 177 or a separate proof mass 177 may be mounted proximate free end 186 of beam 185. The resilience of beam 185 may allow it to act like a spring. Beam 185 may be fixed to a part of rocker arm assembly 110 with a mounting bracket 167. In the examples of FIGS. 16A and 16B, mounting bracket 167 may be mounted to outer arm 113C. But mounting bracket 167 may be affixed to any suitable location on a rocker arm assembly 110.

In some aspects of the present teachings, beam 185 may be two or more centimeters in length. A greater length for beam 185 may increase the power output for cantilever beam vibration-driven piezoelectric generator 137D. But a greater length of beam 185 may create a packaging issue. The packaging issue may be addressed by configuring beam 185 such that the majority of its length runs in parallel with a length of a rocker arm 113. FIG. 16A provides an example in which vibration-driven piezoelectric generator 137D is mounted proximate a second end 112B of a rocker arm 113C and extends proximate a first end 112A of the rocker arm 113C.

In some other aspects of the present teachings, beam 185 is mounted to undergo a wide range of motion as rocker arm assembly 110 cycles. FIG. 16B provides an example in which beam 185 is mounted proximate a first end 112A of a rocker arm 113 that is distal from a second end 112B of the rocker arm 113 at which the rocker arm 113 is pivotally mounted. A large range of motion may increase the amount of energy available in beam 185.

In some other aspects of the present teachings, beam 185 is mounted proximate a first end 112A of a rocker arm 113, which is on the same side of rocker arm assembly 110 as a valve 103. FIG. 16B also provides an example with this type of mounting location. Mounting on the same side as valve 103 may facilitate actuating a vibration-driven piezoelectric generator 137C with vibrations generated when valve 103 lands on its seat 109. In any case, a vibration-driven piezoelectric generator 137C may be tuned in relation to the vibrations available on a rocker arm assembly 110.

In some aspects of the present teachings, generator 137 may be an electromagnetic generator 137B. In some of these aspects, electromagnetic generator 137B may be configured for cam shaft 125 to do work on electromagnetic generator 137B. In some of these aspects, electromagnetic generator 137B may be configured to be actuated by a reciprocating motion of rocker arm assembly 110. FIG. 17 provides an example.

In the example of FIG. 17, a coil 187 of an electromagnetic generator 137B may be mounted on a lifter 115. A magnet 189 for electromagnetic generator 137B may be mounted off rocker arm assembly 110. In this example, magnet 189 may be mounted to a surface 104 of an engine block (not shown) through a mounting bracket 191. Magnet 189 may be an electromagnet or a permanent magnet.

In some other aspects of the present teachings, an electromagnetic generator 137B may include a component coupled to rotate or pivot in sync with a rotation or pivoting of a component of a rocker arm assembly 110. A rotating part of the rocker arm assembly 110 may be a cam roller 121A or a trunnion 119B fixed to rotate in sync with cam roller 121A. A pivoting part of the rocker arm assembly 110 may be an elephant's foot 155, a rocker arm 113, or any other part of the rocker arm assembly 110 mounted on a trunnion 119 or a rocker shaft 111. A pivoting part may alternatively be a part that pivots on a lifter 115, an HLA 117, or other fulcrum.

FIGS. 18 and 19 provide examples in which an electromagnetic generator 137B is mounted to one side of a rocker arm 113. In the example of FIG. 18, a magnet 189 may be fixed to trunnion 119, which may extend outside of rocker arm 113. Generator coils 187 may be fixed to rocker arm 113. In the example of FIG. 19, this arrangement may be reversed. Generator coils 187 may be fixed to trunnion 119 while magnet 189 may be fixed to rocker arm 113. It should be appreciated that these examples may be extended to any location on rocker arm assembly 110 where a first part rotates or pivots on a trunnion 119, a rocker shaft 111, or on another shaft.

A bearing (not shown) may be provided to facilitate pivoting of rocker arm 113 on trunnion 119. Trunnion 119 may be an axle. In some aspects of the present teachings, trunnion 119 may be coupled to a cam roller 121A. This may allow electromagnetic generator 137B to cycle faster than the rotation of cam 123, although in this example the driving force for electromagnetic generator 137B would not be the lifting force applied by cam 123. By contrast, in some aspects of the present teachings, electromagnetic generator 137B is driven by the lifting force applied by cam 123. In these later teachings, electromagnetic generator 137B may be configured to cycle with the same frequency as cam 123.

In some aspects of the present teachings, generator 137 may be a spring-mass electromagnetic generator 137E. FIG. 20 provides an example. As shown in FIG. 20, spring-mass electromagnetic generator 137E may include a proof mass 177 and a spring 179 within a housing 183. Proof mass 177 may be a magnet 189

As shown in FIG. 20, spring-mass electromagnetic generator 137E may be mounted on an elephant's foot 155. Elephant's foot 155 may be position to act on a valve 103 (not shown in these figures). Other locations that may be suitable for spring-mass electromagnetic generator 137E include on a rocker arm 113, on an HLA 117, and on a lifter 115.

In some aspects of the present teachings, the spring constant for spring 179 of spring-mass electromagnetic generator 137E may be selected in relation to the mass of proof mass 177 and the damping provided by coils 187 such that generator 137E is driven primarily by reciprocations of rocker arm assembly 110 induced by rotation of cam 123. An alternative may be to select the spring constant for spring 179 such that generator 137E is driven primarily by vibrations. This latter alternative may be more suited for piezoelectric generator 137C of FIG. 15. Give equal spring constants, proof mass weights, and locations on rocker arm assembly 110, the forces produced in piezoelectric generator 137C of FIG. 15 and electromagnetic generator 137E of FIG. 20 may be similar. But the useful work done by these forces is limited by the displacement they produce in a generator 137. For piezoelectric generator 137C of FIG. 15, that distance is the distance through which piezoelectric material 181 may be compressed. The compression of piezoelectric material 181 may be limited to 0.5% or less its thickness. For electromagnetic generator 137E of FIG. 20, the distance through which work can be done is related to the range of motion of proof mass 177 and can be a much greater distance. Therefore, electromagnetic generator 137E of FIG. 20 may be better suited to being driven primarily by reciprocations of rocker arm assembly 110. Tuning of spring 179 and proof mass 177 for responsiveness to vibrations may produce a much higher cycling for a generator 137, but with less energy production per cycle.

In some aspects of the present teachings, electrical device 151 may include a sensor. In some of these aspects, the sensor may be a position sensor. The position sensor may sense the relative position of two parts of a rocker arm assembly 110. The position sensor may be a latch position sensor. Alternatively, the position sensor may sense the relative position of a part of rocker arm assembly 110 relative to a part external to rocker arm assembly 110. In some aspects of the present teachings, electrical device 151 may include a transmitter. A transmitter may transmit a signal from a sensor. In some aspects of the present teachings, electrical device 151 may include an amplifier. An amplifier may be configured to amplify the output of a sensor.

In some aspects of the present teachings, electrical device 151 may include a receiver. A receiver may receive a signal to switch a latch position. Electrical device 151 may be configured to operate a solenoid in response to the signal. A receiver in conjunction with a generator 137 on rocker arm assembly 110 may be used to enable wireless electronic control of rocker arm assembly 110. The wireless signals may be initiated from an external source, such as an engine control unit (ECU).

According to some aspects of the present teachings, a rocker arm assembly 110 may be made using a rocker arm 113 put into production for use independently from rocker arm assembly 110 or any other rocker arm assembly that includes a generator 137. Rocker arms for commercial applications are typically manufactured using customized casting and stamping equipment requiring a large capital investment. The present teachings provide rocker arm assemblies 110 having one or more rocker arms 113 in which the rocker arms 113 may have undergone casting and stamping operations according to designs that do not include adaptations for receiving components of generator 137. In some aspects of these teachings, the rocker arm assemblies also include HLAs 117 that also may have undergone casting and stamping operations according to designs that do not include adaptations for receiving components of generator 137.

FIG. 21 provides a flow chart of a method 200 applying this concept. Method 200 begins with act 201, a design operation in which a rocker arm assembly may be designed in detail without specifications for a generator. The method continues with act 203, building casting and stamping equipment sufficient for implementing the design of act 201. Act 205 is using that equipment to manufacture rocker arms 113. Act 207 is building a valvetrain 101 having rocker arm assemblies 110 that incorporate the rocker arms 113 produced by act 205. Act 207 may include machining operations that modify the rocker arms 113 to receive generators 137.

Act 207 may include installing a piezoelectric generator 137A within a hydraulic chamber 148 to provide an HLA 117 as shown in one of FIGS. 5A, 5B, and 8. The HLA 117 may have been designed without adaptations for the piezoelectric generator 137A. Machining operations may be used to form bores and screw holes for wiring 145 and for attaching piezoelectric generator 137A. The HLAs 117 of FIGS. 9 and 14 may also be made by modifying HLA parts made according to prior designs.

Act 207 may include forming a bore in a rocker arm 113. A circular bore may be formed in the side of a rocker arm 113 currently in production to receive a piezoelectric generator 137A as shown in FIG. 11. Mounting adapter 169 may be press fit into the circular bore.

Act 207 may include attaching a generator 137 to rocker arm assembly that is functional without the generator 137. Vibration-driven piezoelectric generator 137C, cantilever beam vibration-driven piezoelectric generator 137C, and spring-mass electromagnetic generator 137E are all examples that may lend themselves to being attached to pre-existing parts with only simple machining operations.

Other generators 137 described herein may be installed without significantly modifying rocker arms 113 or an HLA 117. For example piezoelectric generator 137A of FIG. 10 may be installed by replacing an elephant's foot 155 with a different elephant's foot 155.

The components and features of the present disclosure have been shown and/or described in terms of certain embodiments and examples. While a particular component or feature, or a broad or narrow formulation of that component or feature, may have been described in relation to only one embodiment or one example, all components and features in either their broad or narrow formulations may be combined with other components or features to the extent such combinations would be recognized as logical by one of ordinary skill in the art. 

1. A valvetrain, comprising: a cam shaft on which is mounted an eccentrically shaped cam; a poppet valve; a rocker arm assembly configured to engage the cam as the cam shaft rotates and operative to actuate the valve; a generator operative to convert mechanical energy into electric energy; and an electrical device, which is distinct from the generator, mounted on the rocker arm assembly; wherein a portion of the generator comprising a pole is mounted on the rocker arm assembly; the generator is configured to power the electrical device, the configuration including an electrical connection between the electrical device and the pole; and the generator is driven by the cam.
 2. (canceled)
 3. A valvetrain according to claim 1, wherein: the generator is an electromagnetic generator comprising a coil and a magnet configured to move relative to one another in a first direction as the cam is rising off base circle and in the opposite direction as the cam is descending toward base circle; and the coil is mounted to the rocker arm assembly.
 4. A valvetrain according to claim 1, wherein: the rocker arm assembly comprises a cam roller configured to follow the cam; the generator is an electromagnetic generator comprising a coil and a magnet configured to undergo relative rotation in sync with the cam roller.
 5. A valvetrain according to claim 1, wherein the pole and the electrical device and are held in rigid relationship to each other through the rocker arm assembly.
 6. A valvetrain according to claim 1, further comprising an energy storage device selected from the group consisting of batteries and capacitors mounted on the assembly and electrically coupled to both the generator and the electrical device.
 7. A valvetrain according to claim 1, wherein the electrical device comprises a solenoid.
 8. (canceled)
 9. A valvetrain according to claim 1, wherein: the rocker arm assembly comprises an elephant's foot; and the generator comprises a component mounted on the elephant's foot.
 10. A valvetrain according to claim 1, wherein: the rocker arm assembly comprises a first part mounted on a second part that is an axle, trunnion, or rocker shaft; the mounting of the first part on the second part permits relative rotation of the first part and the second part; and the generator comprises a first component coupled to the first part and a second component coupled to the second part.
 11. A valvetrain according to claim 1, wherein the generator comprises a piezoelectric material configured to undergo compression in response to the cam rising off base circle and expansion in response to the cam descending toward base circle.
 12. A valvetrain according to claim 1, wherein the rocker arm assembly is operative to transmit force from the cam by one or more pathways and the generator is a piezoelectric generator configured in one of those pathways.
 13. A valvetrain according to claim 1, wherein the generator is a piezoelectric generator positioned within a pathway along which the rocker arm assembly transmits mechanical energy from the cam shaft to a valve spring.
 14. A valvetrain according to claim 1, wherein: the assembly comprises a rocker arm and a fulcrum on which the rocker arm pivots; and the generator is a piezoelectric generator configured to undergo a compressive force in proportion to force of the rocker arm on the fulcrum.
 15. (canceled)
 16. A valvetrain according to claim 1, wherein: the rocker arm assembly comprises a first part mounted on a second part that is an axle, trunnion, or rocker shaft; and the generator is a piezoelectric generator positioned to transmit force between the first part and the second part.
 17. A valvetrain according to claim 1, wherein the generator is a piezoelectric generator positioned between a rocker arm and a lifter in a configuration enabling transmission of mechanical force between the rocker arm and the lifter to take place through the piezoelectric generator.
 18. A valvetrain according to claim 1, wherein: the generator is a bending force-driven piezoelectric generator operative to produce power when bent; and the piezoelectric generator is coupled to bend in conjunction with a movement of the rocker arm assembly.
 19. (canceled)
 20. (canceled) 